Fluid Dynamics of Gas Exchange in High-Frequency Oscillatory Ventilation: In Vitro Investigations in Idealized and Anatomically Realistic Airway Bifurcation Models

Heraty, Kevin B.; Laffey, John G.; Quinlan, Nathan J.

doi:10.1007/s10439-008-9557-1

Cited by 27 publications

(25 citation statements)

References 32 publications

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“…The strong counter flow in the HFOV case is easily visible at the flow reversal phase while the flow in the NB case is one-way at almost every time step. This remark is consistent with Heraty et al (2008) and Lunkenheimer et al (1972) who concluded that the increase of oscillation frequency will increase the counter flow effect. For the HFOV case, higher velocity profiles are observed at the core of the tube and thinner boundary layers near the wall.…”

Section: Fluidsupporting

confidence: 80%

“…Krishnan and Brower (2010) developed a review study and concluded that HFOV treatment is superior than conventional mechanical ventilation (CV) and should be considered promising but experimental mode of ventilation for the treatment of plenty lung diseases. Heraty et al (2008) experimentally investigated the flow field during HFOV using particle image velocimetry on realistic and idealized bifurcation cast models in order to understand localized fluid dynamics mechanisms and concluded that the increase of oscillation frequency will increase the duration of the reverse flow near the walls (counter flow effect). The same study also highlighted the importance of secondary flows, flows at different directions than the primary flow, and recirculation in the HFOV flow field.…”

Section: Gas Transport Through Hfovmentioning

confidence: 99%

See 1 more Smart Citation

Particle Transport and Deposition under High-Frequency Oscillatory Ventilation and Normal Breathing

Makris

Pilou

Neofytou

et al. 2013

Aerosol Science and Technology

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The fluid mechanics of high-frequency oscillatory ventilation (HFOV) for gas transport in the pulmonary region of the human lungs have been thoroughly studied by different methods. The major concept of HFOV adaptation is to push gas into further generation of the bronchial tree, with adequate gas mixing and small tidal volume. However, particle transport and deposition under HFOV is a rarely studied case where different mechanisms, compared to the mechanisms of gas transport, may associate. The target of this study is to numerically compare the efficiency of particle drug deposition under HFOV to normal breathing (NB) and to further clarify the mechanisms of particle transport and deposition under oscillating flows. A fully Eulerian computational fluid particles dynamic (CFPD) model is used for studying the transport and deposition of several sizes of inertia particles, under different transient flow conditions, inside a single physiologically realistic bifurcation created by generations G3-G4 of the human lung. An insight into the particle dynamics under high-frequency oscillating flow fields is given and the results showed that the highly oscillating field (HFOV) displayed stronger secondary flows, thinner boundary layers, and strong counter flow that accumulate and deposit particles further than a lower frequency oscillatory field (NB).

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Section: Fluidsupporting

confidence: 80%

Section: Gas Transport Through Hfovmentioning

confidence: 99%

Particle Transport and Deposition under High-Frequency Oscillatory Ventilation and Normal Breathing

Makris

Pilou

Neofytou

et al. 2013

Aerosol Science and Technology

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“…They observed reverse flow near the walls when the driving velocity was small, postulating that this may be responsible for the occurrence of pendelluft at the bifurcations. Heraty et al (41) carried out PIV experiments to measure the velocity field and secondary flows in both idealized and realistic single airway bifurcations under HFOV conditions. They observed the coaxial counterflow feature; that is, the flow in the core region of the airway lumen lags behind the flow in the near-wall peripheral region at flow reversal during change of the respiratory phase.…”

Section: High-frequency Oscillatory Ventilationmentioning

confidence: 99%

Airway Gas Flow

Tawhai

Lin

2011

Comprehensive Physiology

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Local characteristics of airflow and its global distribution in the lung are determined by interaction between resistance to flow through the airways and the compliance of the tissue, with tissue compliance dominating flow distribution in the healthy lung. Current understanding is that conceptualizing the airways of the lung as a system of smooth adjoined cylinders through which air traverses laminarly is insufficient for understanding flow and energy dissipation and is particularly poor for predicting physiologically realistic transport of particles by the airflow. With rapid advances in medical imaging, computer technologies, and computational techniques, computational fluid dynamics is now becoming a viable tool for providing detailed information on the mechanics of airflow in the human respiratory tract. Studies using such techniques have shown that the upper airway (specifically its development of a turbulent laryngeal jet in the trachea), airway geometry, branching and rotation angle, and the pattern of joining of successive bifurcations are important in determining airflow structures. It is now possible to compute airflow in physical domains that are anatomically accurate and subject specific, enabling comparisons among intersubjects, that among subjects of different ages, and that among different species.

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“…The respiratory flows along realistic and idealized model channel were investigated simultaneously. The amount of secondary flow was higher in realistic geometry than in the idealized geometry with quite different structure (18) . The flow structure in each generation might be influenced by the flow from higher and lower generations (19) .…”

Section: Introductionmentioning

confidence: 82%

Investigation of Gas Redistribution in Doubly Bifurcated Respiratory Channel of Human Lung

Ahmmed

Hirahara

Yamamoto

et al. 2011

JBSE

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An oscillatory flow in human lung was investigated with a real scale model channel experimentally. One objective of the present study is to clarify the gas exchange mechanism in the peripheral channel, e.g. from the 18-th to 20-th generations, which are the leading region of gas exchanges. The second object is the inspection of the flow convection under the HFOV (high frequency oscillatory ventilation) condition. The experiment was carried out with a real scale two-dimensional model of airway, instead of using a similarity model, in order to take into account the practical condition of HFOV. The velocity profiles were obtained from ensemble mean measurements and the air trajectories were demonstrated with the ensemble mean velocities in the test section. It was confirmed that the air trajectories of expiration were deviated from those of inspiration in the intermediate zone of our channel. It was predicted that a convective flow mixing might be took place depending on the geometric configuration and the asymmetric compliance ratios of the bronchioles.

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Fluid Dynamics of Gas Exchange in High-Frequency Oscillatory Ventilation: In Vitro Investigations in Idealized and Anatomically Realistic Airway Bifurcation Models

Cited by 27 publications

References 32 publications

Particle Transport and Deposition under High-Frequency Oscillatory Ventilation and Normal Breathing

Particle Transport and Deposition under High-Frequency Oscillatory Ventilation and Normal Breathing

Airway Gas Flow

Investigation of Gas Redistribution in Doubly Bifurcated Respiratory Channel of Human Lung

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